diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux')
-rw-r--r-- | sysdeps/unix/sysv/linux/dl-early_allocate.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/dl-early_allocate.c b/sysdeps/unix/sysv/linux/dl-early_allocate.c new file mode 100644 index 0000000000..52c538e85a --- /dev/null +++ b/sysdeps/unix/sysv/linux/dl-early_allocate.c @@ -0,0 +1,82 @@ +/* Early memory allocation for the dynamic loader. Generic version. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Mark symbols hidden in static PIE for early self relocation to work. */ +#if BUILD_PIE_DEFAULT +# pragma GCC visibility push(hidden) +#endif +#include <startup.h> + +#include <ldsodefs.h> +#include <stddef.h> +#include <string.h> +#include <sysdep.h> +#include <unistd.h> + +#include <brk_call.h> +#include <mmap_call.h> + +/* Defined in brk.c. */ +extern void *__curbrk; + +void * +_dl_early_allocate (size_t size) +{ + void *result; + + if (__curbrk != NULL) + /* If the break has been initialized, brk must have run before, + so just call it once more. */ + { + result = __sbrk (size); + if (result == (void *) -1) + result = NULL; + } + else + { + /* If brk has not been invoked, there is no need to update + __curbrk. The first call to brk will take care of that. */ + void *previous = __brk_call (0); + result = __brk_call (previous + size); + if (result == previous) + result = NULL; + else + result = previous; + } + + /* If brk fails, fall back to mmap. This can happen due to + unfortunate ASLR layout decisions and kernel bugs, particularly + for static PIE. */ + if (result == NULL) + { + long int ret; + int prot = PROT_READ | PROT_WRITE; + int flags = MAP_PRIVATE | MAP_ANONYMOUS; +#ifdef __NR_mmap2 + ret = MMAP_CALL_INTERNAL (mmap2, 0, size, prot, flags, -1, 0); +#else + ret = MMAP_CALL_INTERNAL (mmap, 0, size, prot, flags, -1, 0); +#endif + if (INTERNAL_SYSCALL_ERROR_P (ret)) + result = NULL; + else + result = (void *) ret; + } + + return result; +} |